Conjugated polymers, such as polypyrroles, polythiophenes, polyanilines, polyphenylenes and derivatives thereof are known for their electroactive nature, which is widely described in review works such as the "Handbook of Organic Conducting Polymers" (T. J. Skotheim editor, Marcel Dekker, New York, 1986). These polymers are obtained in the form of a film on an electrode, in the form of self-supporting films or alternatively in the form of a composite when combined with a polycationic or polyanionic polymer and behave like organic electrodes, which charge up according to an anodic oxidation process, by insertion of ions from the electrolytic medium. This electrochemical process is reversible, the reduction leading to the expulsion of the ions from this conjugated polymer or from the electroactive composite.
A second generation of conjugated polymers was then described in the literature, obtained by the covalent grafting, on to the monomer units of the polymers, of functional groups capable of providing these electroactive conjugated polymers with an additional function. By way of example, electrocatalytic metal complexes were grafted on to the monomer units of the polypyrrole, specific complexing macrocycles were grafted on to the polypyrrole or polythiophene chains for the recognition of cations in an electrolytic medium, and chiral groups were grafted on to polythiophenes for the recognition of optically active anions. All of these routes of functionalization have also formed the subject of development procedures detailed in the literature (F. Garnier, Angew. Chemie, 1989, 101, 529; A. Deronzier, J. C. Moutet, Acc. Chem. Res. 1989, 22, 249; J. Roncali, Chem Rev., 1992, 92, 711).
In the last few years authors have become interested in the use of functionalized conductive polymers for the development of analyte scavengers, in particular for diagnostic purposes. However, as indicated in Patent Application EP 0,314,009, it was commonly accepted by the scientific community that pyrrole polymers substituted either on the nitrogen atom or directly on the carbon atoms of the pyrrole ring were not good candidates for the development of analyte scavengers, in particular on account of the loss of conductivity of said polymers when functional groups are introduced on to the heteroatomic ring. In order to overcome this problem, the authors of this patent application thus envisaged the use of 2,5-di(2-thienylpyrrole) polymers which were grafted in the 3-position of the pyrrole ring with a reactive moiety with which an organic molecule could become covalently bonded. It should, however, be noted that on account of the hydrophobicity of the thiophene rings, the polymers described cannot be conductive and electroactive in aqueous media and consequently do not appear to be suitable for the detection and/or characterization of an analyte in a biological sample (see J. Roncali et al., Chem. Comm., 1986, page 783 and G. Tourillon et al., Electronal. Chem., 161, 407, 1984).